GUI Programming with GTK+

Transcription

1 GUI Programming with GTK+ Second Part Florian Pelz

2 Today Distribution Miniature IMS Internationalization Other features

3 Last time We talked about how to write a C program, how to use C and GTK+ for creating windows and widgets, how to incorporate the Glade editor into the workflow and developing a small software program.

4 Issues However, end users don t like having to compile their software before using it and compiling with many long terminal commands is annoying even for developers.

5 Maintainers Maintainers fill a vital role concerning the software s infrastructure. In a software projekt, maintainers make sure the software is easy to configure, compile, test etc., runs on all supported systems, can be easily delivered to end users and the remaining infrastructure (Web site, wiki, bug tracker, ) works, good and only good patches get accepted, the change log and news are kept clean, all authors and copyrights get mentioned, Maintainers for an operating system use this infrastructure to distribute the software to end users.

6 Build Systems A build system compiles the software automatically. Independent of the Integrated Development Environment. Necessary for lagge projects. Well-known build systems are: GNU Autotools CMake Waf, Scons Ant, Gradle, Maven Meson

7 GNU Autotools autoconf automatizes finding operating system tools, determining operating system features, compile time configuration (such as compiler selection). automake automatizes compiliing the software, testing (proving?) the software, installing the software and releasing a version of compilable source code. Traditional and common. For the actual building of the software, make is used.

8 GNU Meson Autotools autoconf meson automatizes finding operating system tools, determining operating system features, compile time configuration (such as compiler selection). automake meson automatizes compiliing the software, testing (proving?) the software, installing the software and releasing a version of compilable source code. Traditional and common. For the actual building of the software, make ninja is used.

9 Meson meson is an easy-to-use build system. Meson is declarative and not Turing-complete. Many GNOME projects are switching from Autotools to Meson. Introduction Handout. More information on

10 Version Control Systems Version control systems like git manage multiple source code versions. They make it possible for multiple developers to work in parallel on the same code, for a single developer to work in parallel on different parts of the code, for anyone to easily check out an old version and to find the version which introduced a bug.

11 For end users: Package managers On GNU systems, software is typically distributed with a package manager. Packages mainly consist of either tested, automated scripts for compiling and installing software or the finished files created by such a script, placed at locations appropriate for the operating system. Generally packages are created by running a build system. Details depend on the package manager.

12 For end users: Bundles For most systems there are also self-containing application bundles (which may need to be installed before use). A bundle is a directory containing both the software and all its dependencies. Metadata and configuration files may be located outside the bundle. Such a bundle can be offered e.g. for download on the Web, in an app store, or on physical media. Security risk? ( Flatpak) Ship together with an offer of making available the complete and corresponding GTK+ source code for an appropriately low fee (changed source code must be usable).

13 Miniature IMS For practice we re building a small inventory management system for a fictitious copyshop. Since this is a big project, we re going to use objects: Inheritance. Modularization. Other languages.

14 Localization Refers to adapting the software to the local language and customs, i.e. translation, representation of date and time, units of measure, decimal marks, For short: l10n.

15 Internationalization Refers to offering the infrastructure necessary for localization. For short: i18n. PO files (like de.po ) contain translations for all visible strings. In code, label = gtk_label_new (" Hello World"); must be replaced by label = gtk_label_new (_(" Hello World")); The _() function of GNU Gettext supplies the appropriate translation. _() can also be interpreted as marking the string. Similar markings exist to give context to translators such as where in the program this string is being used. See handouts.

16 Accessibility That is making software accessible to assistive technology. Accessibility means: compatibility with screen readers, compatibility with large text sizes, color choice and contrast, configurable time limit for double clicks, flashing the screen on error, For short: a11y. Mostly automatic in GTK+. Still, ATK should be used e.g. for specifying the relationship between widgets.

17 Unit tests Detect program errors through automated testing. GLib offers a framework for unit testing. Meson can be used to execute tests written with it. See for example the source code of GTK+ for an example testsuite. reftests compare the user interface pixel by pixel used in GTK+.

18 Static and Dynamic Analysis Static: Without running the program. Use multiple compilers. coala for detecting coding style errors. Dynamic: Valgrind. Profiler.

19 Profiling A profiler measures which parts of the program are executed frequently and how long they take and/or other resource consumption like memory usage. This tells you which code to spend time on to optimize performance.

20 gtk-doc Code can be documented inside the source files. gtk-doc generates HTML documentation from the source. The documentation can be read e.g. using Devhelp. But GNOME Builder is using restructuredtext/sphinx, Builder s main author Christian Hergert still is not entirely happy.

21 Introspection Allows for querying information on types and classes: method names, signals, properties, This enables automatic generation of bindings for other programming languages.

22 D-Bus For Inter-Process Communication (IPC). Also used for communicating with the desktop environment: To activate program actions, for notifications,

23 CSS CSS allows for changing the style of GTK+ widgets and also configurable keyboard shortcuts in GTK+.

24 More stuff GSettings store settings, old program state etc. GResource can be used to compile data into the executable file. GtkInspector shows and changes GTK+ informationen of running programs. g_autoptr can be used to automatically free memory when leaving code blocks. Mind the Human Interface Guidelines. Some things don t need a GUI.

25 Further reading Book on GLib and GTK+: glib-gtk-dev-platform.pdf For C++ programmers: https: //developer.gnome.org/gtkmm-tutorial/stable/ Internationalization: https: //wiki.gnome.org/translationproject/devguidelines

26 Image sources etc. Slide design based on Construction site caution sign taken from effectively public domain (CC0) by dchandir.

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